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authorAlison Schofield <amsfield22@gmail.com>2017-01-21 19:28:52 -0800
committerJonathan Cameron <jic23@kernel.org>2017-01-22 13:21:41 +0000
commitd5d24bcc0a10a755ee77149e2f311c4ddafc19db (patch)
tree0f6a7162c45ffd3c6b6a758ffc567958b42762ae /drivers/iio/industrialio-trigger.c
parentdfebd8d81dc69afa9f20459ec9839f857f8c135f (diff)
downloadlinux-d5d24bcc0a10a755ee77149e2f311c4ddafc19db.tar.gz
iio: trigger: close race condition in acquiring trigger reference
In iio_trigger_write_current() we find the trigger we want while holding mutex on the list of triggers, but we don't actually do a get on it while holding mutex. We wait until further validations are completed and we're sure it's the one we want. Race condition is that it could be freed by the time we do the get. Solution is to grab the trigger (iio_trigger_get) as soon as we find it while holding mutex on the list of triggers. If later we decide it's not the right one, put it back. (iio_trigger_put). Signed-off-by: Alison Schofield <amsfield22@gmail.com> Suggested-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio/industrialio-trigger.c')
-rw-r--r--drivers/iio/industrialio-trigger.c21
1 files changed, 13 insertions, 8 deletions
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 978729f6d7c4..d0d869eb48f7 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -147,8 +147,7 @@ static struct iio_trigger *__iio_trigger_find_by_name(const char *name)
return NULL;
}
-static struct iio_trigger *iio_trigger_find_by_name(const char *name,
- size_t len)
+static struct iio_trigger *iio_trigger_acquire_by_name(const char *name)
{
struct iio_trigger *trig = NULL, *iter;
@@ -156,6 +155,7 @@ static struct iio_trigger *iio_trigger_find_by_name(const char *name,
list_for_each_entry(iter, &iio_trigger_list, list)
if (sysfs_streq(iter->name, name)) {
trig = iter;
+ iio_trigger_get(trig);
break;
}
mutex_unlock(&iio_trigger_list_lock);
@@ -416,20 +416,22 @@ static ssize_t iio_trigger_write_current(struct device *dev,
}
mutex_unlock(&indio_dev->mlock);
- trig = iio_trigger_find_by_name(buf, len);
- if (oldtrig == trig)
- return len;
+ trig = iio_trigger_acquire_by_name(buf);
+ if (oldtrig == trig) {
+ ret = len;
+ goto out_trigger_put;
+ }
if (trig && indio_dev->info->validate_trigger) {
ret = indio_dev->info->validate_trigger(indio_dev, trig);
if (ret)
- return ret;
+ goto out_trigger_put;
}
if (trig && trig->ops->validate_device) {
ret = trig->ops->validate_device(trig, indio_dev);
if (ret)
- return ret;
+ goto out_trigger_put;
}
indio_dev->trig = trig;
@@ -441,13 +443,16 @@ static ssize_t iio_trigger_write_current(struct device *dev,
iio_trigger_put(oldtrig);
}
if (indio_dev->trig) {
- iio_trigger_get(indio_dev->trig);
if (indio_dev->modes & INDIO_EVENT_TRIGGERED)
iio_trigger_attach_poll_func(indio_dev->trig,
indio_dev->pollfunc_event);
}
return len;
+
+out_trigger_put:
+ iio_trigger_put(trig);
+ return ret;
}
static DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,